Blank cartridge for training purposes

ABSTRACT

A blank cartridge for training purposes in the form of an elongated case made of thermoplastic synthetic resin and forming a hollow simulated projectile and a powder chamber. The case is provided with weakening lines for providing a predetermined rupturing of the case in the form of external longitudinal grooves or slots extending from the tip of the simulated projectile over substantially the entire length of the projectile. The powder chamber is provided with a powder charge mass of at least 10 g. and internal longitudinal grooves may also be provided.

United States Patent Gawlick et al.

BLANK CARTRIDGE FOR TRAINING PURPOSES Heinz Gawlick; Rudolf Stahlmann, both of Furth, Bay, Germany Assignee: Dynamit Nobel Aktiengesellschalt Filed: Mar. 21, 1973 Appl. No.: 343,186

Inventors:

Foreign Application Priority Data Mar. 23, 1972 Germany 2214092 U.S. CI 102/39; 102/43 P; 102/41 Int. Cl. F42b 5/20; F42!) 5/30 Field of Search 102/43 P, 41, 39, 927

References Clted UNITED STATES PATENTS 12/1959 Ringdal 102/39 51 May 13, 1975 3,144,827 8/1964 Boutwell 102/39 3.410.213 11/1968 Stadler et a1 i 102/39 3,435,765 4/1969 Gawlick 102/39 Primary Examiner-Robert F. Stahl Attorney, Agent, or Firm-Craig & Antonelli [57] ABSTRACT A blank cartridge for training purposes in the form of an elongated case made of thermoplastic synthetic resin and forming a hollow simulated projectile and a powder chamber. The case is provided with weakening lines for providing a predetermined rupturing of the case in the form of external longitudinal grooves or slots extending from the tip of the simulated projectile over substantially the entire length of the projectile. The powder chamber is provided with a powder charge mass of at least 10 g. and internal longitudinal grooves may also be provided.

27 Claims, 10 Drawing Figures BLANK CARTRIDGE FOR TRAINING PURPOSES The present invention relates to a blank cartridge for training purposes having a case of a thermoplastic syn thetic resin forming a powder chamber and a hollow simulated projectile. the cartridge being provided at the tip with defined weakening or rupturing lines. and enclosing a powder charge mass of at least ltl g.

In accordance with (icrman Patent 95tl.7lo. blank cartridges for training purposes are known wherein the powder and projectile cavities are made from an integrally produced case of a thermoplastic synthetic resin. such as polyethylene. polyvinyl chloride or the like. The plastic case is connected flush with a metallic bottom piece at the rear end. or inserted in a metallic jacket which surrounds the powder chamber and which has been subsequently formed at the front end by coldworking into a cartridge shoulder. At the front end of the plastic case. i.c.. at the tip of the simulated projectile. defined weakening lines are formed where the case is ruptured under the effect of the gas pressure of the powder charge reacting during firing. thus permitting the escape of the produced powder gases.

These conventional blank cartridges for training purposes have been suitable for smaller calibcrs with a powder charge mass of less than l0 g. However. when increasing the mass of the powder charge in case of larger calibers. such as. for example 35 mm.. in order to make it possible to fire the training cartridge without difficulties from automatic firearms. problems are encountered. On the one hand. for operating the automatic mechanism. a relatively large amount of gas is required within a very short time period, which would actually be available, considering the size of the powder charge. but which escapes so gradually from the ruptured tip of the training cartridge that the flawless functioning of the automatic mechanism is not always ensured. On the other hand, the backup of the powder gases in the training cartridge causes a correspondingly great pressure stress on the simulated projectile, which latter is thereby often torn partially or even completely from the remaining portion of the case. Such an uncontrolled destruction of the training cartridge can. however. not be tolerated in practice. since. in view of the case residues remaining in the cartridge chamber, a subsequent training cartridge can no longer be satisfactorily loaded into the firearm in some cases. Thus. the automatic firing sequence of the firearm is interrupted and a correspondingly cumbersome and timeconsuming cleaning of the firearm is necessary.

Additionally. the danger of an excessive destruction of the training cartridge increases with increasing length of the simulated projectile. which length necessarily increases with increasing calibers. This results because. due to the manufacturing process. an increasing number of irregularities occurs in the wall thickness of the hollow simulated projectile. resulting in an in creased possibility of uncontrolled rupturing and dc tachment of the simulated projectile.

Therefore. the present invention has as an object thereof the avoiding of the above-described disadvantages of the conventional blank training cartridge with a case made of a thermoplastic synthetic resin having a powder chamber and a hollow simulated projectile provided at the tip with defined weakening lines. wherein the mass of the enclosed powder charge is at least It) g.

in accordance with the present invention. weakening lines are formed as external longitudinal grooves cmanating from the tip and extending at least substantially over the entire simulated projectile. Under the effect of the pressure of the powder gases. the simulated projectile is ruptured in a defined manner in the longitudinal grooves. i.c.. it is disintegrated into strips of a predetermined shape and predetermined dimensions. which strips remain connected with the other portions of the case with their rear ends. The thus-obtained long exhaust slots make it possible for the powder gases to escape quickly in an advantageous manner so that. on the one hand. the operation ofthc automatic mechanism of the firearm is ensured and. on the other hand. a quick pressure relief of the simulated projectile is obtained and thus the danger of the detachment of more or less large sections of the simulated projectile is avoided.

According to a feature ofthc present invention. if the cartridge case is additionally provided as is known in a conventional manner with a case shoulder and a case neck between the case shank proper. which essentially forms the powder chamber. and the simulated projectile. the external longitudinal grooves are extended over the case neck up to the region of and in close proximity with the case shoulder so as to provide an even more rapid escape of the powder gases as is desirable in individual cases.

In accordance with another feature of the present invention, the simulated projectile is additionally provided with internal longitudinal grooves extending at least substantially over its entire length and optionally also over the case neck in the proximity of the case shoulder. This is provided. for example. in order to advantageously influence the stress distribution in the simulated projectile caused by the manufacturing process wherein the plastic case is produced according to the injection molding method. in the direction toward an optimum mechanical strcss-bcaring capacity of the simulated projectile. By extending. according to a further feature of the invention. the internal longitudinal grooves past the case neck into the zone of the case shoulder. the additional advantage is obtained that the case shoulder under the pressure effect of the powder gases present in the case is pressed more strongly against the corresponding wall portion of the cartridge chamber of the firearm, whereby the rearward sealing of the cartridge chamber. i.e.. in the direction toward the breech. is desirably improved and the undesired cscape of the powder gases toward the rear is reduced.

Depending on the requirements in each particular case. the external and internal longitudinal grooves can be formed of the same or also of a differing cross section. The grooves can be disposed. for example. as seen in cross section. in opposition to each other in such a manner that the bridge remaining between the two grooves is disposed exactly in the center of the wall of the simulated projectile. According to a feature of the invention. in order to provide an additional improvement of the seal between the training cartridge and the cartridge chamber. the external and internal longitudinal grooves. as seen in cross section. can instead be disposed so that they are in alternating succession about the case wall. This provides the effect that only the external longitudinal grooves act as defined predetermined rupturing lincs, while the internal longitudinal grooves enhance the deform-ability of the strips of material present between the external longitudinal grooves and thus press these strips more strongly against the wall of the cartridge chamber under the pressure effect of the powder gases.

A similar effect can be attained. according to a further feature of the present invention. by forming the external longitudinal grooves with varying depths. For this purpose, a deep groove and a shallow groove, or also a deep groove and two shallow grooves, succeed one another alternatingly at mutual spacings. In this connection, the deep grooves act as predetermined disintegrating or rupturing lines, while the shallow grooves again enhance the deformability of the remaining strips of material and thus the pressing thereof against the wall of the cartridge chamber. ln addition to providing the thus-attained improved seal with respect to rearwardly escaping gases, the shallow external grooves have the additional effect that the contact surface of the remaining strips of material with the wall of the cartridge chamber is reduced and accordingly, the extraction of the fired cartridge, which is still under an internal excess pressure, out of the cartridge chamber is fa cilitated.

In accordance with another feature of the present invention, in order to still further improve the maximally defined rupturing of the longitudinal grooves effective as predetermined rupturing lines, an additional longitudinal notch is provided at the web at the base of the groove, preferably along one of its two longitudinal edges, so that the web, the width of which for manufacturing reasons can be reduced to below a certain minimum amount only with difficulties, does not tear apart somewhere in an uncontrolled manner, but rather is torn off under the effect of the powder gases at one of its longitudinal edges and is then flipped toward the outside about the other longitudinal edge. The additional longitudinal notch can be provided in the external and/or internal longitudinal grooves.

As has been found, especially advantageous conditions are generally attained by providing at least 6 and at most 12 external longitudinal grooves acting as predetermined rupturing lines, wherein the total width of all longitudinal grooves, measured on the outer surface and optionally the inner surface of the simulated projectile, is suitably about 60% of the length of the outer circumference of the simulated projectile. The thickness of the connecting web at the bottom of the longitudinal grooves effective as predetermined rupturing lines must not be too large, on the one hand, in order to obtain the desired rupturing effect. On the other hand, this thickness must not be chosen to be too small, either, in order to exclude an unintended rupturing due to inherent stresses, for example during storage of the training cartridge. For the customary materials employed in the projection of the case and the normal stresses, a web thickness of about 0.3 0.6 mm. has proved to be advantageous.

In case the powder charge is accommodated in an additional internal casing closed at the front end, and is thus secured against falling out, as well as penetration of atmospheric humidity, etc., in accordance with German Patent 964,386, it is also possible according to the present invention to provide longitudinal slots in place of the longitudinal grooves effective as predetermined rupturing lines. The exhause slots thus are initially incorporated during the manufacture of the cartridge case, so that a subsequent rupturing during firing is no longer necessary. The width of these slots is determined in correspondence with the respective requirements.

In order to ensure also in case of larger masses of powder charge that the strips of material remaining upon firing between the longitudinal grooves and/or longitudinal slots are not torn off from the remaining portion of the case under any circumstances. these strips can be formed, together with the adjoining case zone, with an enlarged, for example doubled, wall thickness as compared to the normal case, so that after firing, the external shape of the cartridge case including the simulated projectile is unchanged.

These and further objects, features and advantages of the present invention will become more obvious from the following description when taken in connection with the accompanying drawings which show, for purposes of illustration only, several embodiments in accordance with the present invention, and wherein FIG. 1 shows, in the left and right-hand portions thereof respectively, a plan view and a longitudinal sectional view of the front end of a blank cartridge for training purposes in accordance with the present invention;

FIGS. Za-Zg show different cross-sectional shapes of the simulated projectile;

FIG. 3 shows a fragmentary cross-sectional view of the wall of a simulated projectile; and

FIG. 4 shows a fragmentary cross-sectional view of the wall of a simulated projectile with a longitudinal slot.

Referring now to the drawing wherein like reference numerals are utilized to designate like parts throughout the several views, there is shown in FIG. 1, the case of a blank cartridge for training purposes in accordance with the present invention and which includes a simulated projectile l, a neck portion 2, a shoulder portion 3, and a shank portion 4. The simulated projectile l is provided with external longitudinal grooves 5 extending over the case neck 2 up to the region of the case shoulder 3. An internal longitudinal groove 6 is also provided and is indicated by the dashed line and extends approximately from the tip of the simulated projectile 1 up to the zone of the case shoulder 3. The blank training cartridge furthermore includes an outer metal sleeve 7 contacting the case shoulder 3 via a metal ring 8 serving as an abutment. In the interior, there is provided an inner case portion 9 forming a powder chamber for receiving the powder charge, not shown.

As shown in FIG. 2a which illustrates the crosssectional shape of the simulated projectile l, the external longitudinal grooves 5 and the internal longitudinal grooves 6 have differing cross-sectional configurations and a web 10 is disposed approximately in the center of the wall of the simulated projectile 1.

FIG. 2b shows a configuration wherein shallow external longitudinal grooves 12 are provided in addition to the deep external longitudinal grooves ll. However, only the external grooves 11 are effective as actual predetermined rupturing lines, whereas the external longitudinal grooves 12, together with the internal longitudinal grooves 6, effect on the one hand, an easier deformability of the strips of material 13 and thus an improved obturation, and generally are not ruptured. On the other hand, in view of the reduced contact surface and the pressure relief due to the powder gases which escape into the external longitudinal grooves 12, the extraction of the fired cartridge from its chamber is facilitated.

FIG. 20 shows a cross-sectional shape of maximum simplicity, with 6 external longitudinal grooves 11 effective as predetermined rupturing lines. and a smooth inner surface. FIG. 2d shows a modification of FIG. 2: with twice the number of external longitudinal grooves 11, i.e., 12 grooves II and a smooth inner surface.

According to cross-sectional shape embodiment of FIG. 2e, the wall of the simulated projectile is provided with external longitudinal grooves ll effective as predetermined rupturing lines, and the internal longitudinal grooves 6 are disposed respectively between adjacent external grooves, effecting the desired ready deformability of the strip 13 of material.

FIGS. 2f and 2g show a cross-sectional configuration with external and internal longitudinal grooves 5 and 6 of identical shape, wherein the web is arranged in the center of the wall of the simulated projectile 1. In FIG. 2f, an embodiment is shown having 6 predetermined rupturing lines, while in FIG. 2g there is shown a modification with l2 predetermined rupturing lines.

FIG. 3 shows a fragmentary cross-sectional configuration of another embodiment of the present invention wherein a longitudinal notch 14 is provided at a longitudinal edge of the web 10 and FIG. 4 shows an embodiment wherein a longitudinal slot 15 is provided in place of the longitudinal grooves 11.

It can thus be seen that the provision of rupturing or weakening lines in accordance with the present invention ensures proper operation of a blank cartridge for training purposes having a case made of a thermoplastic synthetic resin and forming a hollow simulated projectile and a powder chamber for enclosing a powder charge mass of at least l0 g. Obviously, many modifications and variations of the present invention are possible in the light of the above teachings. It should therefore be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

We claim:

1. Blank cartridge for training purposes comprising an elongated case of thermoplastic synthetic resin, said case forming an elongated hollow simulated projectile and a powder chamber, longitudinal extending rupturing means provided in the wall of said case and extending from the tip of said simulated projectile over at least substantially the entire length of said simulated projectile, said rupturing means being rupturable along the length thereof in response to a predetermined internal gas pressure, and longitudinal extending weakening means provided in the wall of said case for enhancing the deformability of said case, said weakening means being constructed so that the wall portion provided with said weakening means remains intact at the predetermined gas pressure.

2. Blank cartridge according to claim 1, wherein said rupturing means includes a plurality of spaced external longitudinal rupturing grooves in the external wall of said case.

3. Blank cartridge according to claim 2, further cornprising a powder charge mass of at least 10 g. provided in said powder chamber.

4. Blank cartridge according to claim 3, wherein said case includes a case shoulder portion, a case neck portion and a case shank portion, said case shoulder portion and case neck portion being arranged between said case shank portion and said simulated projectile, said external longitudinal grooves extending from said simulated projectile over said case neck portion and into close proximity with said case shoulder portion.

5. Blank cartridge according to claim 4, wherein said weakening means includes a plurality of spaced longitudinal extending weakening grooves in the internal wall of said case and extending at least substantially over the entire length of said simulated projectile.

6. Blank cartridge according to claim 4. wherein said weakening means includes a plurality of spaced longitudinally extending weakening grooves in the internal wall of said case extending at least substantially over the entire length of said simulated projectile and over said case neck portion into close proximity with said case shoulder portion.

7. Blank cartridge according to claim 6, wherein said internal longitudinal weakening grooves extend past the case neck portion into the region of said case shoulder portion.

8. Blank cartridge according to claim 7, wherein said internal longitudinal weakening grooves are disposed between adjacent external longitudinal rupturing grooves about the wall of said casing such that said external and internal longitudinal grooves are arranged in alternating succession about the wall of said casing.

9. Blank cartridge according to claim 4, wherein said external longitudinal rupturing grooves are provided with two longitudinal edge portions terminating in a base portion, said base portion forming a web extending between said two longitudinal edge portions, and a longitudinal extending notch being provided in said web portion adjacent one of said two longitudinal edge portions of said grooves.

10. Blank cartridge according to claim 9, wherein said weakening means includes a plurality of spaced longitudinal extending weakening grooves provided in the internal wall of said case extending at least substantially over the entire length of said simulated projectile.

11. Blank cartridge according to claim 2, wherein said case includes a case shoulder portion, a case neck portion and a case shank portion, said case shoulder portion and case neck portion being arranged between said case shank portion andsaid simulated projectile, said external longitudinal rupturing grooves extending from said simulated projectile over said case neck portion and into close proximity with said case shoulder portion.

12. Blank cartridge according to claim 11, wherein said weakening means includes a plurality of spaced longitudinally extending weakening grooves in the internal wall of said case extending at least substantially over the entire length of said simulated projectile and over said case neck portion into close proximity with said case shoulder portion.

13. Blank cartridge according to claim 12, wherein said internal longitudinal weakening grooves extend past the case neck portion into the region of said case shoulder portion.

14. Blank cartridge according to claim 2, wherein said weakening means includes a plurality of spaced longitudinal extending weakening grooves in the internal wall of said case and extending at least substantially over the entire length of said simulated projectile.

15. Blank cartridge according to claim 14, wherein said internal longitudinal weakening grooves are disposed between adjacent external longitudinal rupturing grooves about the wall of said casing such that said external and internal longitudinal grooves are arranged in alternating succession about the wall of said casing.

16. Blank cartridge according to claim 14. wherein the total width of said external and internal longitudinal grooves is approximately -6070 of the length of the outer circumference of said simulated projectile.

l7. Blank cartridge according to claim 2, wherein said external longitudinal rupturing grooves are provided with two longitudinal edge portions terminating in a base portion. said base portion forming a web ex tending between said two longitudinal edge portions. and a longitudinal extending notch being provided in said web portion adjacent one of said two longitudinal edge portions of said grooves.

18. Blank cartridge according to claim 2. wherein said plurality of spaced external longitudinal grooves is between 6 and 12 longitudinal grooves.

l9. Blank cartridge according to claim 2, wherein the total width of the external longitudinal grooves is approximately 540% of the length of the outer circumference of said simulated projectile.

20. Blank cartridge according to claim 2, wherein said external longitudinal grooves terminate in a base, said base forming a web portion in the wall of the case, said web portion having a case wall thickness of about 0.3-0.6 mm.

21. Blank cartridge according to claim 1, further comprising an elongated casing portion closed at a front end thereof and disposed within said case to form a powder chamber for receiving a powder charge. said rupturing means being in the form of a plurality of spaced longitudinal slots.

22. Blank cartridge according to claim 21, further comprising a powder charge mass of at least 10 g. provided in said powder chamber.

23. Blank cartridge according to claim I, wherein the wall of said case forming said simulated projectile is provided with portions of increased wall thickness disposed between the longitudinal extending rupturing means.

24. Blank cartridge according to claim 1, wherein said rupturing means includes in the external wall of said case a plurality of spaced external longitudinal rupturing grooves of one depth and said weakening means includes in the external wall of said case a plurality of spaced external weakening grooves of another depth.

25. Blank cartridge according to claim 24, wherein said plurality of spaced external longitudinal grooves is between 6 and I2 longitudinal grooves.

26. Blank cartridge according to claim 24, wherein said external weakening grooves extend from the tip of said simulated projectile over at least substantially the entire length thereof.

27. Blank cartridge according to claim 1, wherein said weakening means includes a plurality of spaced longitudinal extending weakening grooves provided in the internal wall of said case extending at least substantially over the entire length of said simulated projectile. i i i 

1. BLANK CARTRIDGE FOR TRAINING PURPOSES COMPRISING AN CLONGATED CASE OF THERMOPLASTIC SYNTHETIC RESIN, SAID CASE FORMING AND ELONGATED HALLOW SIMULATED PROJECTILE AND A POWDER CHAMBER LONGITUDINAL EXTENDING RUPTURING MEANS PROVIDED IN THE WALL OF SAID CASE AND EXTENDING FROM THE TIP OF SAID SIMULATED PROJECTILE OVER AT LEAST SUBSTANTIALLY THE ENTIRE LENGTH OF SAID SIMULATED PROJECTILE, SAID RUPTURING MEANS BEING RUPTURABLE ALONG THE LENGTH THEREOF IN RESPONSE TO A PREDETERMINED INTERNAL GAS PRESSURE, AND LONGITUDINAL EXTENDING WEAKENING MEANS PROVIDED IN THE WALL OF SAID CASE FOR ENHANCING THE DEFORMABILITY OF SAID CASE, SAID WEAKENING MEANS BEING CONSTRUCTED SO THAT THE WALL PORTION PROVIDED WITH SAID WEAKENING MEANS REMAINS INTACT AT THE PREDETERMINED GAS PRESSURE.
 2. Blank cartridge according to claim 1, wherein said rupturing means includes a plurality of spaced external longitudinal rupturing grooves in the external wall of said case.
 3. Blank cartridge according to claim 2, further comprising a powder charge mass of at least 10 g. provided in said powder chamber.
 4. Blank cartridge according to claim 3, wherein said case includes a case shoulder portion, a case neck portion and a case shank portion, said case shoulder portion and case neck portion being arranged between said case shank portion and said simulated projectile, said external longitudinal grooves extending from said simulated projectile over said case neck portion and into close proximity with said case shoulder portion.
 5. Blank cartridge according to claim 4, wherein said weakening means includes a plurality of spaced longitudinal extending weakening grooves in the internal wall of said case and extending at least substantially over the entire length of said simulated projectile.
 6. Blank cartridge according to claim 4, wherein said weakening means includes a plurality of spaced longitudinally extending weakening grooves in the internal wall of said case extending at least substantially over the entire length of said simulated projectile and over said case neck portion into close proximity with said case shoulder portion.
 7. Blank cartridge according to claim 6, wherein said internal longitudinal weakening grooves extend past the case neck portion into the region of said case shoulder portion.
 8. Blank cartridge according to claim 7, wherein said internal longitudinal weakening grooves are disposed between adjacent external longitudinal rupturing grooves about the wall of said casing such that said external and internal longitudinal grooves are arranged in alternating succession about the wall of said casing.
 9. Blank cartridge according to claim 4, wheRein said external longitudinal rupturing grooves are provided with two longitudinal edge portions terminating in a base portion, said base portion forming a web extending between said two longitudinal edge portions, and a longitudinal extending notch being provided in said web portion adjacent one of said two longitudinal edge portions of said grooves.
 10. Blank cartridge according to claim 9, wherein said weakening means includes a plurality of spaced longitudinal extending weakening grooves provided in the internal wall of said case extending at least substantially over the entire length of said simulated projectile.
 11. Blank cartridge according to claim 2, wherein said case includes a case shoulder portion, a case neck portion and a case shank portion, said case shoulder portion and case neck portion being arranged between said case shank portion and said simulated projectile, said external longitudinal rupturing grooves extending from said simulated projectile over said case neck portion and into close proximity with said case shoulder portion.
 12. Blank cartridge according to claim 11, wherein said weakening means includes a plurality of spaced longitudinally extending weakening grooves in the internal wall of said case extending at least substantially over the entire length of said simulated projectile and over said case neck portion into close proximity with said case shoulder portion.
 13. Blank cartridge according to claim 12, wherein said internal longitudinal weakening grooves extend past the case neck portion into the region of said case shoulder portion.
 14. Blank cartridge according to claim 2, wherein said weakening means includes a plurality of spaced longitudinal extending weakening grooves in the internal wall of said case and extending at least substantially over the entire length of said simulated projectile.
 15. Blank cartridge according to claim 14, wherein said internal longitudinal weakening grooves are disposed between adjacent external longitudinal rupturing grooves about the wall of said casing such that said external and internal longitudinal grooves are arranged in alternating succession about the wall of said casing.
 16. Blank cartridge according to claim 14, wherein the total width of said external and internal longitudinal grooves is approximately 5-60% of the length of the outer circumference of said simulated projectile.
 17. Blank cartridge according to claim 2, wherein said external longitudinal rupturing grooves are provided with two longitudinal edge portions terminating in a base portion, said base portion forming a web extending between said two longitudinal edge portions, and a longitudinal extending notch being provided in said web portion adjacent one of said two longitudinal edge portions of said grooves.
 18. Blank cartridge according to claim 2, wherein said plurality of spaced external longitudinal grooves is between 6 and 12 longitudinal grooves.
 19. Blank cartridge according to claim 2, wherein the total width of the external longitudinal grooves is approximately 5-60% of the length of the outer circumference of said simulated projectile.
 20. Blank cartridge according to claim 2, wherein said external longitudinal grooves terminate in a base, said base forming a web portion in the wall of the case, said web portion having a case wall thickness of about 0.3-0.6 mm.
 21. Blank cartridge according to claim 1, further comprising an elongated casing portion closed at a front end thereof and disposed within said case to form a powder chamber for receiving a powder charge, said rupturing means being in the form of a plurality of spaced longitudinal slots.
 22. Blank cartridge according to claim 21, further comprising a powder charge mass of at least 10 g. provided in said powder chamber.
 23. Blank cartridge according to claim 1, wherein the wall of said case forming said simulated projectile is provided with portions of increased Wall thickness disposed between the longitudinal extending rupturing means.
 24. Blank cartridge according to claim 1, wherein said rupturing means includes in the external wall of said case a plurality of spaced external longitudinal rupturing grooves of one depth and said weakening means includes in the external wall of said case a plurality of spaced external weakening grooves of another depth.
 25. Blank cartridge according to claim 24, wherein said plurality of spaced external longitudinal grooves is between 6 and 12 longitudinal grooves.
 26. Blank cartridge according to claim 24, wherein said external weakening grooves extend from the tip of said simulated projectile over at least substantially the entire length thereof.
 27. Blank cartridge according to claim 1, wherein said weakening means includes a plurality of spaced longitudinal extending weakening grooves provided in the internal wall of said case extending at least substantially over the entire length of said simulated projectile. 